Computing systems store information using a variety of storage systems. Storage systems are constructed using a variety of memory technologies including solid-state memory, disk memory, flash memory, optical storage, and magnetic tape. Many storage systems arrange storage space into one or more volumes, with an interface that presents the volume to clients as a block device. For example, many hard disks present a single volume with read and write operations that use a cylinder, head, and sector address. In some environments, a single volume is divided into one or more partitions, and each partition provides a separate amount of data storage. Some storage systems, such as network-attached storage (“NAS”) systems and storage area networks (“SANs”), include an interface that can be used by more than one client, or by more than one client simultaneously.